Preparation and Properties of Green-yellow Reversible Electro-thermochromic Fabric

doi:10.15541/jim20210726

Abstract

Abstract:

Graphene has played a major role in wearable electronic textiles due to its excellent electrical conductivity, superior flexibility and environmental stability. In this work, a green-yellow reversible electrothermochromic fabric was constructed via a facial double side coating. The self-made graphene paste is coated on the surface of polyester fabric by screen printing technology. The hybrid thermochromic ink with reversible color-changing property is coated on the opposite side of the graphene layer by screen printing technology. Structural properties and discoloration principle of the fabric were analyzed. Their thermal and color-changing properties were studied by using infrared thermal imaging and colorimeter. The results show that the graphene forms a conductive layer with a thickness of 250 μm that allows Joule heating to supply the thermal resource for the electrothermochromic behavior. This fabric changes from green to yellow with a gradual heating that exceeded 45 ℃ at 12 V due to the ring closure and opening of crystal violet lactone. Its color change response time is about 15 s, while fading response time is about 27 s. The electro-thermochromic fabric is not disturbed once undergoing a bending angle range from 30° to 180° and the voltage-current curve remains stable. Performance of the fabric does not significantly degrade after 200 heating/cooling continuous cycles. In conclusion, a sensitive electro-thermochromic fabric with good cycle performance from green to yellow with the structure of graphene film‖polyester fabric‖thermochromic film is successfully prepared, which has a high application potential in the fields of military camouflage and wearable display.

Key words: electro-thermochromic fabric, graphene, thermochromic microcapsules, wearable display

CLC Number:

TM911

CHEN Saisai, PANG Yali, WANG Jiaona, GONG Yan, WANG Rui, LUAN Xiaowan, LI Xin. Preparation and Properties of Green-yellow Reversible Electro-thermochromic Fabric[J]. Journal of Inorganic Materials, 2022, 37(9): 954-960.

Figures/Tables 12

Fig. 1 Illustration of the preparation process of graphene electro-thermalchromic fabric and the composition of thermochromic ink

Fig. 2 Photographs and SEM images of a blank polyester fabric, graphene conductive layer and thermochromic layer (a, e, i) Photographs of a blank polyester fabric, graphene conductive layer and thermochromic layer at room temperature; (b, c, d) SEM images of the surface and cross section of the base polyester fabric at different magnifications; (f, g, h) SEM images of the surface and cross section of the graphene conductive layer at different magnifications; (j, k, l) SEM images of the surface and cross section of the thermochromic layer at different magnifications

Fig. 3 XRD patterns of graphene (a), blank polyester fabric (b) and graphene conductive fabric (c)

Fig. 4 Schematic diagram of the color change process (a) and schematic diagram of the heat transfer method (b) of graphene electro-thermochromic fabric

Fig. 5 FT-IR spectra of CVL (a), BPA (b), fluorescent yellow dye (c) and hybrid thermochromic ink before (d) and after (e) heating

Fig. 6 Schematic diagram (a) and physical image (b) of thermochromic ink before and after color change Colorful images are available on website

Fig. 7 Photographs of the the graphene electro-thermochromic fabric during a color-change cycle under an applied voltage of 12 V Colorful images are available on website

Fig. 8 Thermal images of the graphene electro-thermochromic fabric during a cycle under an applied voltage of 12 V Colorful images are available on website

Fig. 9 Temperature-time curve of graphene electro-thermochromic fabric under a current voltage of 12 V

Table 1 Chromaticity parameters of graphene electro-thermochromic fabric

Potential/V	x	y	Y
0	0.0334	0.7485	5.04
12	0.4407	0.5402	53.15

Fig. 10 CIE1931 chromaticity diagram of graphene electro- thermochromic fabric before and after color change

Fig. 11 Stability analysis of graphene electro-thermochromic fabric (a,b) Photographs of the graphene electro-thermochromic fabric bent at a certain degree; (c-h) Images of the graphene electro-thermochromic fabric bending at 0°, 30°, 60°, 90°, 150°, and 180° after voltage being applied; (i) Current-voltage curves of the graphene electro-thermochromic fabric bended at different bending angles. Colorful figures are available on website

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